Mail handling apparatus conventionally includes a franking module organized to print postage stamps and other information (slogans, etc.) on the mail.
In known manner, the information printed during franking includes an enciphered code required by international standards, which enciphered code is computed on the basis of determined parameters (date, postal or “ZIP” code, etc.).
In franking modules that use printing systems that use ink jet technology, it is important for the speed of advance of the mail item, as it goes past the print head, to be substantially constant, even if such a constant speed can be set differently as a function of the mail to be handled.
Document US 2003/0055790 (PITNEY BOWES) describes a mail-handling system including franking means that use ink printing technology and in which generating the enciphered code requires a time lying in the range 200 milliseconds (ms) to 500 ms.
That device therefore has mail drive means adapted to cause the mail to advance at a constant speed at the time at which it is substantially under the print head.
In the PITNEY BOWES arrangement, the mail conveyor module must be slowed down in order to guarantee that it allows the time necessary for computing the above-mentioned enciphered code (that computation must take place before the mail item reaches the print head), and then accelerated so as to impart to the mail items the pre-required constant speed at the time at which franking takes place.
Thus, the PITNEY BOWES mail handling apparatus makes it necessary to brake and to accelerate the advance of the belt, or even to stop it.
Therefore, it does not make it possible to handle mail on the fly.
Also, the PITNEY BOWES mail handling system does not describe taking account of mail item weight, which is required for enciphering the code; it assumes that all of the mail items are of the same weight.
Therefore, such a system cannot handle mail in arbitrarily mixed batches.